Many products sold to consumers have a limited lifetime beyond which the product value is diminished or completely gone. For example, epoxies must be used within a limited time after they are made. Beyond that limited time the epoxy loses its adhesive capability. The date beyond which the product is not useful is typically called the expiration date. Similarly, many foods must be consumed prior to an expiration date, or they will spoil. Some foods will spoil prior to the expiration date if they are not kept within a range of environmental conditions. If such a product is exposed to an environment beyond the acceptable range, for example, if it is overheated in a truck driving through a desert, it will lose the ability to perform or deliver the function that a consumer expects. Pharmaceutical products also have expiration dates beyond which the drug will not function with its maximum efficiency.
Currently, packages with time limitations are often marked with the expiration date. The date may be marked on the container or placed on a printed label, which is attached to the product. Sometimes this date is difficult to locate, unreadable or not present at all. Since some consumers expect the stores remove expired products from the shelves, they do not even look for the expiration date. However, some stores are lax in removing expired products from their shelves. There is no method currently available to determine if the product was exposed to an environment that was detrimental to the product.
It is preferable to have a small, low cost, flexible label which will sense the environment and passage of time to determine if the product useful and indicate with a highly visible light emitting diode if the product is useful to a consumer.